FIG. 3.
Identification of 3Cpro cleavage sites in PTBs. (A) Schematic diagram of 3Cpro cleavage sites in PTBs. The amino acid sequences around the major and minor cleavage sites in PTBs are shown in the single-letter motif. The NLS and RRMs in PTB are indicated by open and solid boxes, respectively, and the sizes of the cleaved products are shown in kilodaltons. Ab, antibody. (B) [35S]methionine-labeled PTB4 and its mutants were incubated with (+) or without (−) 3Cpro at 37°C for 3 h. Protease reactions were stopped by the addition of 2× Laemmli sample buffer, and the samples were analyzed by SDS-PAGE followed by autoradiography.